This constant current source for high voltage loads was obtained from a 1967 General Electric documentation. The components are of the time, but allow equivalents.
This Power supply is intended to Power small loads with currents up to 30 mA. The voltage depends...
This setting appears multiple times on the site from different sources. This is from a 2000 manual...
The transistor in this circuit can be the BC548 or any general-purpose equivalent, and the phone...